feat: debug recording off by default, toggle in settings

- AudioPipeline.debugRecording defaults to false (was true)
- SettingsRepository: persist debug_recording preference
- CallViewModel: debugRecording StateFlow + setter, wired to AudioPipeline
- Only records PCM + RMS when explicitly enabled in settings

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

scripts/build-android-docker.sh

@@ -41,7 +41,7 @@ LOCAL_OUTPUT_DIR="target/android-apk"
 PROJECT_DIR="$(cd "$(dirname "$0")/.." && pwd)"
 LOCAL_KEYSTORE_DIR="$PROJECT_DIR/android/keystore"
 
-SSH_OPTS="-o ConnectTimeout=10 -o LogLevel=ERROR"
+SSH_OPTS="-o ConnectTimeout=10 -o LogLevel=ERROR -o ServerAliveInterval=15 -o ServerAliveCountMax=4"
 
 # ---------------------------------------------------------------------------
 # Helpers